MXPA00006959A - Self-healing optical network - Google Patents

Abstract

A self-healing optical network carrying traffic between first and second optical linear terminals (NODE A, NODE B, NODE C, NODE D). The self-healing optical network including first, second, and third optical switching units (210, 216, 226, 232), first, second, and third spare optical channels (214, 220, 222, 228), and a working optical channel (212, 218, 224, 230). The first, second, and third optical switching units are coupled in a ring configuration using said first, second, and third spare optical channels. The first and second optical switching units are coupled by the first spare optical channel and by the working optical channel. The first and second optical switching units each direct the traffic between the first and second optical linear terminals along the working optical channel or along the second and third spare optical channels in the event the working optical channel is not available.

Description

OPTICAL NETWORK THAT IS COMPOSED BY ITSELF The present invention relates generally to fiber optic networks. Current telecommunication networks employ optical channels to carry traffic between the nodes. Figure 1 is a diagram of a portion of a telecommunications network. Figure 1 shows the optical channel 108 connecting node A with node B, optical channel 116 connecting node A with node D, optical channel 118 connecting node B with node C, and optical channel 126 that connects node C with node D. Each end of an optical channel is terminated by opto-electronic line termination equipment (LTE) or an optical linear terminal (LT) (for example, a point-to-point line termination equipment of Optical Channel 48) for converting and multiplexing the electrical signals into an optical signal for transmission over an optical channel and for converting a received optical signal into electrical signals for transport over the non-optical portions of the telecommunications network. For example, the linear terminal 106 is connected to one end of the optical channel 108 and the linear terminal 112 is connected to the other end of the optical channel 108. The linear terminal 106 receives the electrical signals from the electrical digital cross-connect switch (DXC) 102 and transforms those signals into optical signals for transmission over the optical channel 108. The linear terminal 112 receives the optical signals from the optical channel 108 and transforms those optical signals back into the electrical domain. When there is an interruption in an optical channel, the linear terminals that connect to the optical channel detect the channel failure, by detecting a loss of the signal condition, for example. After detecting a channel fault, the linear terminals send a failure indication to a network management system (not shown). The network management system then directs the DXCs 102, 110, 122, and 130 to redirect traffic to restore the network. A problem with the use of electrical cross-connect switches to reroute traffic when the network experiences a failure in the optical channel is the substantial amount of time it takes for the network to be restored. One solution is to replace the linear terminals with add-drop multiplexers (ADMs) and create a conventional optical ring network, such as a bidirectional line-switched ring (BLSR). This approach reduces the amount of time it takes to restore the network to the range of 100 milliseconds (approximately). However, this approach is costly because ADMs must be purchased to replace the linear terminals. A network design is needed that can quickly recover from an optical channel failure without requiring the replacement of the linear terminals. The present invention provides an optical network that is itself composed of linear terminals that are optically coupled to optical switching units (OSUs), where the optical switching units are connected in an optical ring configuration. The restoration of the network occurs completely in the optical domain, thus significantly reducing the restoration time. The optical network which is composed by itself in accordance with a first embodiment of the present invention, carries the traffic between the first and second optical terminals. The network includes a plurality of optical switching units, including first, second, and third optical switching units, and a plurality of optical reservation channels, and an optical working channel. The plurality of optical switching units are optically coupled in a ring configuration using the plurality of optical reservation channels, so that a spare optical channel is provided between each pair of adjacent optical switching units in the ring configuration. The first optical linear terminal is optically coupled to the second optical linear terminal through a first pair of adjacent optical switching units and the optical working channel or, in the event that the optical working channel is not available, through the plurality of optical switching units and the plurality of optical reservation channels, except the reserve optical channel that is provided between the first pair of adjacent optical switching units. By optionally coupling the first optical linear terminal to the second optical linear terminal, the optical signals can be transmitted from the first optical linear terminal to the second linear terminal - optics The optical switching units can be switched to form a backup ring path using the optical reservation channels. The first linear terminal, after detecting a fault within a working path that connects the first linear terminal with the second linear terminal, sends a data message indicating a failure of the optical channel to an adjacent OSU. Similarly, the second linear terminal sends a data message indicating a failure of the optical channel to an adjacent OSU. After receiving a failure indication, the OSU adjacent to the first linear element switches the traffic from the first linear terminal onto the reserve ring path. The OSU adjacent to the second linear terminal also switches the traffic from the backup ring path to the second linear terminal. In this manner, the reserve ring path is used as an alternative path to carry traffic between the first and second linear terminals. Another embodiment of the invention includes first and second optical networks. A first optical switching unit is coupled to the first and second optical networks. A second optical switching unit is also optically coupled to the first and second optical networks. An optical backup channel is optically coupled between the first and second optical switching units. The first optical switching unit optically couples either the first or second optical network to the backup optical channel, depending on which optical network has experienced a failure. Similarly, the second optical switching unit optically couples either the first or the second optical network to the backup optical channel, depending on which optical network has experienced a failure. In this way, the first and second optical networks share the reserve optical channel. Other features and advantages of the present invention, as well as the structure and operation of the different embodiments of the present invention, are described in detail below with reference to the accompanying drawings. The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present invention, and together with the description, serve additionally to explain the principles and to enable a person skilled in the pertinent art to make use of the invention. Figure 1 illustrates a portion of a telecommunications network. Figure 2 illustrates a first mode of an optical network that is composed by itself, operating in the normal mode. Figure 3 illustrates a cross-connection switch controller. Figures 4A and 4B illustrate the switching tables used by the OCCS controllers. Figure 5 illustrates a processing for composing an optical network. Figure 6 illustrates the first mode of the optical network that is composed by itself, which operates in a failure mode. Figure 7 illustrates a second mode of the optical network that is composed by itself. Figure 8 illustrates a third mode of the optical network that is composed by itself.

Figure 9 illustrates the configuration of optical network 800 when a fault occurs between nodes A and B. Figure 10 illustrates the configuration of optical network 800 when a failure occurs between nodes B and C. The present invention is described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the digit (s) furthest to the left of a reference number identifies the drawing in which the reference number first appears. To more clearly outline the present invention, an effort has been made throughout the specification to adhere the following definitions of terms as consistently as possible. The term "optical channel", "channel", and the equivalents thereof, refer to any type of optical link to carry an optical signal between two points. The present invention provides an optical network that is composed by itself where the restoration occurs completely in the optical domain, thereby significantly reducing the amount of time it takes to reroute traffic. The optical network comprising itself includes linear terminals that are optically coupled to the optical switching units, wherein the optical switching units are connected in a ring configuration. The present invention is described in an exemplary environment consisting of four nodes in the network. The description of the invention in this environment is provided for convenience only and is not intended to be limiting. After reading the following detailed description, it will be apparent to a person skilled in the relevant art how to implement the invention in alternative environments consisting of a ring configuration having an arbitrary number of nodes in the network. Figure 2 illustrates an optical network comprising itself 200 according to a first embodiment of the present invention. The optical network shown in Figure 2 has four nodes (A, B, C, D). Each node includes two linear terminals. Specifically, the node A includes the linear terminals 104 and 106. The node B includes the linear terminals 112 and 114. The node C includes the linear terminals 126 and 128. The node D includes the linear terminals 120 and 124. At each node is provided with an optical switching unit (OSU). Specifically, node A includes OSU 210, node B includes OSU 216, node C includes OSU 232, and dono d includes OSU 226. Each OSU includes a cross-connect switch (OCCS, for its acronyms in English) that is coupled to an OCCS controller. In one embodiment, an OCCS and an OCCS controller form an integral unit. In another embodiment, an OCCS and an OCCS controller exist as two separate units. An OCCS is a device that can switch the optical paths between a plurality of optical ports. In an example, any of the plurality of optical ports can be internally coupled optically to one or more ports inside the OCCS. The OCCS controllers 209, 215, 231, and 225 direct the switching of the OCCSs 211, 217, 233, and 277, respectively. For example, OCCS controllers 209, 215, 231, and 225 send and receive the status and commands of the switch to and from the OCCSs 211, 217, 233, and 227, respectively. State examples and switch commands include coupling and undocking commands. A port coupling command causes an OCCS to optically internally couple a first port of the OCCS to a second port of the OCCS. A port decoupling command causes an OCCS to internally decouple optically a first port of the OCCS from a second port of the OCCS. Figure 3 is a diagram illustrating a more detailed view of the OCCS controller 209. The OCCS controllers 215, 231, and 225 have the same configuration as the OCCS controller 209 and are therefore not shown. The OCCS controller 209 includes a system processor 302, the control logic 304 that will execute the system processor 302, the memory 306 for storing the switching table 308, the OCCS 310 interface for coupling the OCCS 209 controller to the OCCS 211 , and the interface of the data network 312 for coupling the OCCS 209 controller to the communications channel. As shown in Figure 2, each OCCS 211, 217, 233, 227 is optically coupled to the respective adjacent linear terminals. For example, ports 1 and 2 of OCCS 211 are optically coupled to optical terminals 104 and 106, respectively. Ports 2 and 3 of OCCS 217 are optically coupled to linear terminals 112 and 114, respectively. The ports 3 and 4 of the OCCS 233 are optically coupled to the optical terminals 126 and 128, respectively. The ports 5 and 6 of the OCCS 227 are optically coupled to the linear terminals 120 and 124, respectively. The OCCSs 211, 217, 233, 227 are optically coupled in a ring configuration. There is an optical working channel () and an optical reserve channel (S) that are coupled optically between each OCCS. Specifically, the optical working channel 212 is optically coupled between port 3 of the OCCS 211 and port 1 of the OCCS 217. The backup optical channel 214 is optically coupled between port 4 of the OCCS 211 and the port 6 of OCCS 217. Optical work channel 224 is optically coupled between port 4 of OCCS 217 and port 2 of OCCS 233. Backup optical channel 222 is optically coupled between port 5 of OCCS 217 and port 1 of OCCS 233. Optical work channel 230 is optically coupled between port 5 of OCCS 233 and port 4 of OCCS 227. Optical backup channel 228 is optically coupled between port 6 of the OCCS 233 and port 3 of OCCS 227. Optical work channel 218 is optically coupled between port 1 of OCCS 227 and port 6 of OCCS 211. Finally, backup optical channel 220 is optically coupled between port 2 of OCCS 227 and port 5 of OCCS 211. It should be Note that optical work channel 212 and backup optical channel 214 can be carried by separate fiber optic cables, as shown in Figure 2, or can be multiplexed on a single fiber by long wave split multiplexers (WDMs). , for its acronym in English), as shown in Figure 7. Each pair of optical work / reservation channels 218/220, 222/224, and 228/230, can also be carried on separate fiber optic cables, or multiplexed at different wavelengths on a single fiber. The OCCSs 211, 217, 233, and 227 are switched to form the reserve ring path 260, using the reserve optical channels 214, 222, 228, and 220. In other words, the reserve ring path 260 is formed through the OCCS ^ 211 which internally couples port 4 with port 5; the OCCS 217 that internally couples the port 6 with the port 5; the OCCS 233 internally coupling port 1 with port 6 optically; and the OCCS 227 which internally internally couples port 3 with port 2. The OCCSs 211, 217, 233, and 227 are also switched to form four point-to-point work paths 236, 240, 242, and 238 which use four optical work channels 212, 224, 230 and 218. The point-to-point work path 236 is formed by optically coupling the linear terminal 106 with the linear terminal 112. Specifically, the OCCS 211 optically internally couples port 2 with port 3 and OCCS 217 which internally internally couples port 1 with port 2, optically coupling linear terminal 106 with linear terminal 112 through of the optical working channel 212. In a similar way, the working path 238 is formed by means of optically coupling the linear terminal 104 with the linear terminal 120, the working path 240 is formed by means of optical coupling the terminal li neal 114 with the linear terminal 128, and the work path 242 is formed by optically coupling the linear terminal 124 with the linear terminal 126. When one of the point-to-point work paths 236, 240 fails. , 242, or 238 (for example, there is an interruption in one of the optical working channels), the linear terminals that were optically coupled by the work path will be decoupled optically. When this occurs, the present invention establishes an alternative path using a portion of the reserve ring 260 to optically engage the linear terminals affected by the fault. Figure 5 illustrates a procedure for creating an alternative path using the reserve ring 260 when any of the work paths 236, 240, 242, 238 experiences a failure. The procedure starts at step 501 where the control immediately goes to step 502. In step 502, a switching table is created for the controllers 211, 217, 227, and 233. By way of example, in Figures 4A and 4B the switching table for the OCCS controllers 211 and 227, respectively, is shown. A switching table is a table that has at least two columns, an event column 404 and an action column 406. In this example, for each event that an OCCS controller detects, there is a corresponding course of action that the OCCS controller will take .

As shown in Figure 4A, the OCCS controller 211 detects at least two events: (1) a fault in the work path 236; and (2) a fault in the work path 238. Similarly, the OCCS controller 227 detects two events: (1) a fault in the work path 238; and (2) a fault in the work path 242. The OCCS controller 209 detects a fault in the work path 236 by receiving a failure indication from the linear terminal 106 or other reliable, fast fault detection system. To facilitate the understanding of the invention, the invention will be described in the environment where the failure indications are generated by the linear terminals, but in no way is the invention limited to this environment. The controller 209 detects a fault in the work path 238 by receiving a fault indication from the linear terminal 104. Similarly, the OCCS controller 225 detects a fault in the work path 238 by receiving an indication of failure of the linear terminal 120, and detect an indication of failure in the work path 242 by means of receiving a fault indication of the linear terminal 124. In step 504, each OCCS controller 209, 215, 231 and 225 expects that an event occurs. When an OCCS controller detects an event, control goes to step 506.

In step 506, the OCCS controller that detected the event, consults its switching table to determine the action that the switching table tells it to take. The result of these actions is the creation of an alternative point-to-point path that avoids a fault in a work path. For example, assuming that the work path 238 experiences a fault, then the OCCS controller 209 receives a failure indication from the linear terminal 104 and the OCCS controller 225 receives a fault indication from the linear terminal 120. After receiving the indications of failure, both controller 209 and controller 225, respond in accordance with their switching tables (see Figures 4A and 4B, respectively). In accordance with the switching table for the OCCS 209 controller, the OCCS 209 controller instructs the OCCS 211 to internally disconnect port 4 from port 5, which internally decouples port 1 from port 6, and which internally port 1 to port 4. In accordance with the switching table for the OCCS 225 controller, the OCCS 225 controller tells the OCCS 227 to internally decouple port 2 from port 3, which internally decouples the port 1 of port 6, and internally coupling port 6 with port 3. Figure 6 illustrates the reconfiguration of optical network 200 after a failure is detected in optical work channel 218.

After the OCCS controllers 209 and 225 respond to a fault in the optical working channel 238, an alternative path is created that optically couples the terminal 104 to the terminal 120, using a portion of the path of the backup ring 260 Specifically, the linear terminal 104 is optically coupled to the linear terminal 120 through the reservation optical channels 214, 222, and 228. The amount of time it takes to create an alternate path through the switching Optical, in accordance with the present invention, is significantly faster than in conventional methods to reroute traffic based on digital electrical cross-connect switches, because the restoration is made in the optical layer and tables are used of switching status previously determined. Figure 7 illustrates a second embodiment of the present invention. As shown in Figure 7, the DMs 702, 706 are placed between the OCCS 211 and the OCCS 217 to multiplex the optical working channel 212 and the backup optical channel 214 over the optical fiber 704. Similarly, the WDMs 708, 712 are placed between the OCCS 211 and the OCCS 227 to multiplex the optical working channel 218 and the backup optical channel 220 over the optical fiber 710. The WDMs' 714, 718 are placed between the OCCS 217 and the OCCS 233 for multiplexing the optical working channel 224 and the backup optical channel 222 on the optical fiber 716. The WDMs 720, 724 are placed between the OCCS 227 and the OCCS 233 to multiplex the optical working channel 230 and the channel reserve optical 228 over optical fiber 722. This second embodiment of the present invention functions to provide a ring configuration of the OSUs, which can be switched optically to provide a reservation path through the optical reservation channels. around the ring configuration. The OSUs can also be switched to provide work paths between the linear terminals. In this way, the process shown in Figure 5, as described above, also applies to this WDM embodiment of the present invention and will be apparent to a person skilled in the relevant art. Figure 8 illustrates another embodiment of the present invention. Figure 8 is a diagram of an optical network comprising itself 800 having two optical networks which are themselves composed of 802 and 804, wherein the networks 802 and 804 share the reserve optical channel 860. By means of making the two optical networks share an optical reserve channel, saving costs. The backup optical channel 860 can be coupled optically within the network 802 or the network 804 by the OCCSs 852 and 834. For example, the network 802 can use the backup optical channel 860 if there is an interruption in the network between the nodes A and F, the nodes E and F, or the nodes D and E. Similarly, the network 804 can use the reserve optical channel 860 • if there is an interruption in the network between nodes A and B, the 5 nodes B and C, or nodes C and D. The individual optical networks 802 and 804 are composed by themselves using the same basic procedure illustrated in Figure 6. In other words, OCCSs controllers detect network failures and then tell their corresponding optical cross-connect switches that • make the necessary optical couplings to avoid faults, according to a previously defined switching table that exists for each OCCS controller. The OCCS 850 and 840 controllers detect seven network failures. These failures include: (1) failure between nodes A and B; (2) failure between nodes B and C; (3) failure between nodes C and D; (4) failure between nodes D and E; (5) failure between nodes E and F; (6) failure between nodes F and A; and (7) failure between nodes A and D. 20 The OCCS 850 controller can detect a fault between nodes A and B because the linear terminal 854 or other reliable, fast fault detection device sends notifications of a fault to the OCCS 850 controller. The OCCS 840 controller detects a fault between the nodes a and B because the OCCS 850 controller sends a message through the data network 892 to the OCCS 340 controller, which indicates that a failure occurred between nodes A and B when the OCCS 850 controller detects that failure. The OCCS controllers 850 and 840 can detect a fault between the nodes B and C by causing the OCCSs 870 and / or 882 controllers to transmit a message indicating a fault between the nodes B and C through the data network 892 both the OCCS 850 controller, and the 840 controller. The OCCS controllers 870 and 882 are aware of the faults between the nodes B and C because they receive the failure indications from the linear terminals 872 and 886, respectively. The OCCS controller 840 can detect a fault between the nodes C and D because the linear terminal 844 sends the failure notifications to the OCCS 840 controller. The OCCS 850 controller detects a fault between the nodes C and d because, when the controller OCCS 840 detects this failure, the OCCS 840 controller sends a message through the data network 892 to the OCCS 850 controller, indicating the failure. In a similar manner, OCCSs 850 and 840 controllers detect faults between nodes D and E, nodes E and F, and nodes F and a. In order to illustrate the operation of optical network 800, two failure scenarios will be described: (1) a fault between nodes A and B; and (2) a fault between nodes B and C.

When a fault occurs between the nodes A and B, the linear terminal 854 of the linear terminal 868 is optionally decoupled. As described above, the OCCSs 850, 870, and 840 controllers detect the fault. After detecting it fails, the OCCSs controllers 850, 870, and 840 each consult their respective internal switching tables and instruct the OCCSs 852, 874, and 834 to commute accordingly. Specifically, the OCCS 850 controller instructs the OCCS 852 to optically internally couple port 1 with port 6, optically coupling the linear terminal 854 with the backup optical channel 860. The OCCS 840 controller OCCS 834 is instructed to optically internally couple port 2 with port 4, optically engaging reserve optical channel 860 with backup optical channel 888. Finally, the OCCS 870 controller signals the OCCS 874 which internally connects port 2 with port 5 optically, optically coupling the linear terminal 868 with the reserve optical channel 876. After the OCCSs 852, 874, and 834 carry out the operations of coupling of the ports, the linear terminal 854 is optically coupled to the linear terminal 868, using the optical reservation channels 860, 888, and 876. In this way, failure between the nodes A is prevented and B. This can be seen in Figure 9, which illustrates the reconfiguration of the optical network 800 after a fault between the nodes A and B. When a fault occurs between the nodes B and C, the linear terminal 872 of the linear terminal 886 is decoupled optically. described earlier, the OCCSs 850, 870, 882, and 840 controllers detect the failure. After detecting the failure, the OCCSs controllers 850, 870, 882, and 840 consult their respective internal switching tables and instruct the OCCSs 852, 874, 880, and 834 to commute accordingly. Specifically, the OCCS controller 870 instructs the OCCS 874 to internally internally couple the port 3 with the port 6, optically coupling the linear terminal 872 with the optical reserve channel 866. The OCCS controller 882 tells OCCS 880 to optically internally couple port 4 with port 1, optically coupling linear terminal 886 with optical reserve channel 888. OCCS 840 controller tells OCCS 834 to internally couple Optically port 4 with port 2, optically coupling the backup optical channel 860 with the backup optical channel 888. Finally, the OCCS 850 controller instructs the OCCS 852 to internally couple optically port 3 with port 6, optically coupling the backup optical channel 860 with the optical reservation channel 866. After the OCCSs 852, 874, 880, and 834 perform In the coupling operations of the ports, the linear terminal 872 is optically coupled to the linear terminal 886, using the optical reservation channels 888, 860, and 866. In this way, failure between the nodes B and C. This can be seen in Figure 10, which illustrates the reconfiguration of optical network 800 after a failure between nodes B and C. In a similar way, failures between nodes C and D, nodes are avoided D and E, the nodes E and F, the nodes F and A, and the nodes A and D. Although different embodiments of the present invention have been described above, it should be understood that they have been presented by way of example, and not limitation. Those skilled in the relevant art will understand that different changes can be made in form and detail therein, without departing from the spirit and scope of the invention, as defined in the following claims. In this way, neither the extent nor the scope of any of the exemplary embodiments described above should be limited, but should be defined only in accordance with the following claims and their equivalents.

Claims (34)

1. CLAIMS 1. An optical network comprising itself carrying traffic between first and second optical linear terminals, comprising: a plurality of optical switching units including first, second, and third optical switching units; a plurality of optical reservation channels; and an optical working channel; the plurality of optical switching units being optically coupled in a ring configuration using the plurality of optical reservation channels, so that a spare optical channel is provided between each pair of adjacent optical switching units in the ring configuration; and the first optical linear terminal being optically coupled with the second optical linear terminal through the first pair of adjacent optical switching units and the optical working channel or, in the event that that optical working channel is not available, to through the plurality of optical switching units and the plurality of optical reservation channels, except the reserve optical channel that is provided between the first pair of adjacent optical switching units. The optical network which is composed per se according to claim 1, wherein the first pair of adjacent optical switching units comprises the first and second optical switching units, the first optical switching unit comprising a first switch optical cross-connection sensitive to a first cross-connect optical switch controller; and the second optical switching unit comprising a second cross-connect optical switch responsive to a second cross-connect optical switch controller. The optical network which is composed per se according to claim 2, wherein the first optical linear terminal is optically coupled to the first optical cross-connect switch, and the second optical linear terminal is optically coupled to the second cross-connect optical switch. 4. The optical network which is composed per se according to claim 3, wherein the first cross-connect optical switch controller receives a first indication of failure when a fault occurs in the optical working channel. The optical network comprising itself according to claim 4, wherein the first optical linear terminal transmits the first fault indication to the first controller of the optical transverse connection switch. 6. The optical network comprising itself according to claim 4, wherein the second cross-connect optical switch controller receives a second fault indication when a fault occurs in the optical working channel. The optical network which is composed per se according to claim 6, wherein the second optical linear terminal transmits the second fault indication to the second controller of the optical transverse connection switch. The optical network comprising itself according to claim 5, wherein the first cross-connect optical switch controller includes a first switching table, and the second cross-connect optical switch controller includes a second table of switching, each of the first and second switching tables having an event column and an action column. The optical network comprising itself according to claim 8 wherein, after receiving the first indication of failure, the first controller of the cross-connect optical switch consults the first switching table and sends a corresponding command to an action in the first switching table, to the first cross-connect optical switch. 10. The optical network comprising itself according to claim 1, wherein the first optical linear terminal is optically coupled to a first port of the first optical switching unit, and the second optical linear terminal is coupled in a manner optical to a first port of the second optical switching unit, the optical working channel optically coupling a second port of the first optical switching unit with a second port of the second optical switching unit; and the first optical switching unit optically coupling the first port of the first optical switching unit to the second port of the first optical switching unit, and the second optical switching unit optically coupling the first port of the second optical switching unit. optical switching to the second port of the second optical switching unit, optically coupling the first linear terminal with the second linear terminal through the optical working channel, the first optical switching unit, and the second switching unit optics. The optical network that is composed per se according to claim 10, wherein the optical reserve channel provided between the first and second optical switching units optically couples a third port of the first switching unit optical with a third port of the second optical switching unit, a first optical reserve channel of. the plurality of optical reservation channels optically coupled to a fourth port of the first optical switching unit, and a second optical reserve channel of the plurality of optical reservation channels optically coupled to a fourth port of the second unit of optical switching, wherein the first optical switching unit optically couples the third port of the first optical switching unit to the fourth port of the first optical switching unit and the second optical switching unit optically couples the third port of the second optical switching unit to the fourth port of the second optical switching unit. The optical network comprising itself according to claim 11, wherein, when the optical working channel experiences a fault, the first optical switching unit optical uncouples the third port of the first optical switching unit of the fourth port of the first optical switching unit, and optically couples the first port of the first optical switching unit to the fourth port of the first optical switching unit, thereby routing the traffic around the fault. 13. The optical network comprising itself according to claim 1, wherein the first linear terminal is an opto-electronic line terminal element. 14. The optical network comprising itself according to claim 1, characterized in that it further comprises a first wavelength division multiplexer (WDM) and a second WDM, wherein the first and second WDMs multiplex the optical channel of work and the optical backup channel that is provided between the first pair of optical switching units on an optical fiber. 15. An optical network that is composed by itself, comprising: a first optical network; a second optical network; a first optical switching unit that is optically coupled to the first and second optical units; a second optical switching unit that is optically coupled to the first and second optical networks; and a backup optical channel that is optically coupled between a first port of the first optical switching unit and a first port of the second optical switching unit, wherein the first optical switching unit optically couples the first network Optical to the backup optical channel, when the first optical network experiences a failure, the first optical switching unit optically couples the second optical network to the backup optical channel, when the second optical network experiences a fault, the second switching unit optically couples the first optical network to the optical reserve channel, when the first optical network experiences a failure; and the second optical switching unit optically couples the second optical network to the backup optical channel, when the second optical network experiences a failure. 16. The optical network that is composed by itself in accordance with claim 15, wherein the first optical network comprises first and second linear terminals, and the second optical network comprises third and fourth linear terminals, wherein the first linear terminal is optically coupled to a second port of the first optical switching unit, the third linear terminal is optically coupled to a third port of the first optical switching unit, the second linear terminal is optically coupled to a second port of the second optical switching unit, and the fourth linear terminal is coupled in a manner optical to a third port of the second optical switching unit. 17. The optical network comprising itself according to claim 16, wherein the first optical network further includes a first optical working channel that is optically coupled to a fourth port of the first optical switching unit, and the first optical switching unit optically couples its second port with its fourth port, thereby optically coupling the first linear terminal with the first optical working channel. 18. The optical network comprising itself according to claim 17, wherein the second optical network further includes a second optical working channel that optionally couples to a fifth port of the first optical switching unit, and the first optical switching unit optically couples its third port with its fifth port, optically coupling the third linear terminal with the second optical working channel. 19. The optical network comprising itself according to claim 17, wherein the first optical switching unit receives a fault indication when a fault is detected in the first optical working channel. 20. The optical network comprising itself according to claim 19, wherein the first linear terminal detects the fault and transmits the fault indication to the first optical switching unit. 21. The optical network comprising itself according to claim 19 wherein, after receiving the fault indication, the first optical switching unit optically couples its first port with its second port, coupling by means of the same optically the first linear terminal with the optical reserve channel. 22. The optical network comprising itself in accordance with claim 19 wherein, after receiving the failure indication, the first optical switching unit transmits a message indicating the failure in the optical working channel to the second Optical switching unit through the data network. 23. In an optical network having a plurality of optical switching units, including first, second, and third optical switching units, a method for composing the optical network itself, comprising the steps of: coupling optically the optical switching units in a ring configuration, using a plurality of optical reservation channels, so that the reserve optical channel is provided between each pair of adjacent optical switching units in the ring configuration; Optically coupling a first linear terminal to a second linear terminal through the first optical switching unit, the second optical switching unit, and an optical working channel, wherein the first and second optical switching units are adjacent to each other. the ring configuration; and when a fault occurs in the optical working channel, switching the first and second optical switching units to optically couple the first linear terminal to the second linear terminal through the plurality of optical switching units and all the optical channels of reserves, except the optical reserve channel between the first and second optical switching units. 24. The method of compliance with the claim 23, characterized in that it further comprises the step of switching the plurality of optical switching units, to form a reserve ring path using the plurality of optical reservation channels. 25. The method of compliance with the claim 23, wherein the optical switching unit comprises a first cross-connect optical switch responsive to the first cross-connect optical switch controller, and the second optical switch unit comprises a second cross-connect optical switch responsive to a second switch controller optical cross connection. 26. The method according to claim 25, characterized in that it further comprises the step of transmitting a first fault indication to the first controller of the cross-connect optical switch, after detecting a fault in the optical working channel. 27. The method according to claim 26, wherein the step for transmitting the first fault indication is performed by the first optical linear terminal. 28. The method of compliance with the claim 26, characterized in that it further comprises the step of transmitting a second fault indication to the second controller of the cross-connect optical switch, after detecting the fault in the optical working channel. 29. The method of compliance with the claim 28, wherein the step for transmitting the second fault indication is made by the second optical linear terminal. 30. The method of compliance with the claim 29, wherein the first cross-connect optical switch controller includes a first switching table, and the second cross-connect optical switch controller includes a second switching table, each of the first and second switching tables having a column of event and an action column. 31. The method of compliance with the claim 30, characterized in that it further comprises the steps of consulting the first switching table and transmitting a command corresponding to an action in the first switching table to the first optical cross-connect switch, after receiving the first indication of failure. 32. The method according to claim 31, characterized in that it further comprises the steps of consulting the second switching table and transmitting a command corresponding to an action in the second switching table to the second optical cross-connect switch, after receiving the second indication of failure. 33. A method for sharing a backup optical channel between first and second optical networks, wherein the backup optical channel is optically coupled between a first optical switching unit and a second optical switching unit, and wherein the first optical network includes a first linear terminal and a second linear terminal, and the second optical network includes a first linear terminal and a second linear terminal, the method comprising the steps of: receiving a fault indication in the first optical switching unit that indicates a failure in one of the first and second optical networks; optically coupling the first linear terminal of the first optical network with the reserve optical channel, if the fault indication indicates a fault in the first optical network; optically coupling the first linear terminal of the second optical network with the reserve optical channel, if the fault indication indicates a fault in the second optical network; and transmitting a message from the first optical switching unit to the second optical switching unit through a data network, wherein the message indicates a failure in the first optical network if the failure indication indicates a failure in the first network or if the message indicates a fault in the second optical network, if the fault indication indicates a fault in the second optical network. 34. A method for sharing a first optical reservation channel between optical networks first and second, wherein the first optical backup channel is optically coupled between a first optical switching unit and a second optical switching unit, and wherein the first optical network includes a second backup optical channel and a third optical backup channel. , and the second optical network includes a fourth reserve optical channel and a fifth reserve optical channel, the method comprising the steps of: detecting a fault in the first optical network or the second optical network; Optically coupling the second and third optical reservation channels to the first optical reserve channel, when a fault is detected in the first optical network; and optically coupling the fourth and fifth optical reservation channels to the first optical reserve channel, when a failure is detected in the second optical network.